Weaving is a harmful (negative) status effect in Minecraft Java Edition 1.21.
minecraft:weaving
Give Weaving II for 60 seconds (Java Edition 1.13+; duration in seconds, then amplifier where 0 = level I):
Remove the effect from the nearest player:
Weaving causes the affected entity to spread cobwebs when it dies, a sticky parting gift associated with the bogged in trial chambers.
Attacks from the bogged, the mossy skeleton variant in trial chambers and swamps, apply Weaving for a short time. No potion or item grants it to players directly.
The cobwebs only appear on death, so Weaving is mostly a terrain hazard that gums up the floor mid-fight. Cobwebs slow everything including you, so kill affected mobs away from your escape route.
The effect ID for Weaving is minecraft:weaving. Java Edition 1.13+ /effect commands use this namespaced form.
Run /effect give @p minecraft:weaving 60 1 to get Weaving II for 60 seconds. The first number is the duration in seconds; the second is the amplifier (0 = level I, 1 = level II). Remove it with /effect clear @p minecraft:weaving.
Weaving is a harmful (negative) status effect in Minecraft Java Edition, based on its registry category (harmful).
When the affected entity dies, cobwebs generate around it. It is applied by the bogged, a skeleton variant found in trial chambers and swamp biomes.
Get hit by a bogged. The effect lasts a short while and only does something if the affected entity dies during that window, dropping cobwebs on the spot.